This invention relates to a temperature control device for a constant temperature chiller unit which provides thermal medium fluid such as cold water of constant temperature toward a semiconductor manufacturing device, a laser machine, or miscellaneous scientific or chemical instruments in a fluid circulating mode, and to a temperature control device for an automatic vending machine which stores articles therein and can change itself into a cooling mode and heating mode in relation to the season or other conditions.
In the prior constant temperature chiller unit, thermal medium fluid such as pure water or xe2x80x9cfluorinertxe2x80x9d (supplied by 3M corporation) is supplied through a refrigerating system comprised of a compressor, a condenser and an evaporator for fron gas (Freon gas). In this process, high temperature fron gas compressed by a compressor is liquidized by a condenser into liquid fron, and the liquid fron absorbs heat from the surroundings when it is evaporated by an evaporator, whereby produced is a temperature medium fluid such as low temperature pure water or xe2x80x9cfluorinertxe2x80x9d.
When the range of the allowable temperature is limited in a small range, such as in a semiconductor manufacturing device which requires an accurate setting of plus and minus 1 degree C., if the refrigerator (evaporator) is operated at a maximum power for cooling, the temperature of the thermal medium fluid goes down too low, thereby being overcooled. For compensating this problem, a constant temperature tank having a buffer capacity of three to five times of cold water flow per minute is disposed, and the tank is provided with an electrical heater for controlling the temperature. Then, extra electrical power is necessary, whereby the overall size of the apparatus becomes large and additional cost for setting and operation becomes necessary.
Referring to FIG. 8, there is shown a constant temperature tank with a heater of prior art. The constant temperature tank 16 produces cold water by a refrigerating circuit 1 comprised of a compressor 12, a condenser 14 and an evaporator 20. The produced cold water is supplied to the external secondary heat load 24 such as a semiconductor manufacturing device by the pump 22, and is circulated within the cold water circulating circuit 3. In the refrigerating circuit 1, there is provided a dryer 15, and in the cold water circulating circuit 3, there are provided a pressure controller 17, a relief valve 19 and pressure gauge G. Within the constant temperature tank 16, there are provided a sensor for detecting overheating and freezing, and a sensor for detecting water level of the tank. Each sensor is connected to an overheat and freezing monitor (arrow A) and to a water level monitor (arrow B), respectively. To the bottom of the tank 16, a drain circuit 28 is connected and a drain valve 29 is disposed for controlling the drain port (arrow C).
Thus, high temperature fron gas (refrigerant) compressed by a compressor 12 in the refrigerating system is liquidized by a condenser 14 into liquid fron, and the liquid fron absorbs heat from the surroundings when it is evaporated by the evaporator 20, whereby cold water is produced. On the other hand, the condenser 14 is exposed to high temperature. For cooling the condenser 14, a cooling circuit 2 comprised of a water cooling type cooler 26 is provided. The cooler 26 is cooled by any of cooling tower water, factory circulating water or underground water. In this circuit 2, cooling water is circulated by operating a flow switch 25 and a control valve 27, so that the condenser 14 is cooled.
However, when the range of the allowable temperature is limited in a small range, such as in a semiconductor manufacturing device, if the evaporator 20 (refrigerator) is operated at a maximum power for cooling, the temperature of the thermal medium fluid goes down too low, thereby being overcooled. For compensating this problem, an electrical heater 50 is attached to the constant temperature tank 16 for controlling its temperature. The heater 50 is also used for raising the temperature of thermal medium fluid during its starting mode. As a result, extra electrical power is required, whereby an additional cost is required.
In other methods for controlling the temperature, a hot gas bypass method and a refrigerator ON and OFF method are known. However, in the former method, cooling and heating should be alternately exchanged, whereby the response of temperature control is poor and the bypass valve is not reliable so that it often fails. In the latter method, a large capacity buffer tank should be disposed, so that the overall size becomes larger and the accuracy of the temperature control becomes poor.
In an automatic vending machine which can change itself into a cooling mode and heating mode in relation to the season, a powerful heater is inevitable. Accordingly, extra electrical power is required and thus an additional cost is required.
Japanese unexamined patent publication No. Hei 9-72644 entitled xe2x80x9cCold water circulation supply machine for scientific and chemical machinesxe2x80x9d and Japanese unexamined patent publication No. Hei 9-196512 entitled xe2x80x9cCooling liquid supply devicexe2x80x9d relate to a constant temperature chiller unit as a cold water supply device.
It is a first object of the present invention to provide a temperature control device for thermal medium fluid in which an electrical heater is eliminated from the constant temperature tank thereby reducing the electrical power so that it can improve the accuracy and response of the device.
It is a second object of the present invention to provide a temperature control device for thermal medium fluid in which the constant temperature tank is eliminated thereby reducing the overall size of the device.
It is a third object of the present invention to provide a temperature control device for thermal medium fluid in which the working range is extended from xe2x88x9240 degree C. to 60 degree C. relative to the prior art.
It is a fourth object of the present invention to provide a temperature control device for thermal medium fluid in which the electrical power in a starting mode is considerably reduced.
It is a fifth object of the present invention to provide a power saving type temperature control device for an automatic vending machine which stores articles therein and can change itself into a cooling mode and heating mode in relation to the season or other conditions.
A first object of the present invention is achieved by the device in which a heat exchanger is interposed within a compression circuit between a compressor and a condenser so that the compression circuit becomes a primary circuit of the heat exchanger, and a bypass circuit is disposed at the downstream side of a pump. Through the bypass circuit, thermal medium fluid passes through a secondary circuit of the heat exchanger toward a circulation circuit, and fluid flow in the bypass circuit is controlled by a flow control valve. Heated thermal medium fluid by the heat exchanger is introduced into the circulation circuit. Thus, the temperature of thermal medium fluid supplied to an external secondary heat load is controlled.
Based upon above characteristics of the first embodiment of the invention, a part of the heat of the high temperature fron gas compressed by the compressor is given to the thermal medium fluid (water) which is supplied to the external secondary heat load so that the temperature of the overcooled thermal medium fluid (cold water) cooled by the regrigerating circuit is raised and controlled within a predetermined temperature range. Thus, the accuracy and response of the device are improved. Since the electrical heater in the prior art is eliminated, the electrical power and cost are reduced.
The second object of the present invention is achieved by the device in which the evaporator is comprised of multi-tube type cylindrical evaporator and this cylindrical evaporator works as the constant temperature tank. The capacity of the cylindrical evaporator is preferably 0.1 to 2.0 times of cold water flow per minute, more preferably 0.25 to 1.5, further preferably 0.5 to 1.0. Thus, according to the invention, it becomes possible to eliminate the constant temperature tank so that the overall size of the device is reduced.
The third object of the present invention is achieved by a similar device as the first aspect of the invention. In addition to the first aspect, a cooling circuit of the condenser is disposed. Further, a second bypass circuit is interposed between the downstream side of the condenser and the downstream side of the evaporator, and a capillary tube and an electromagnetic valve are disposed within the second bypass circuit. Fluid flow in the second bypass circuit is controlled by the electromagnetic valve, whereby the cooling temperature cooled by the evaporator is controlled and overheating of the compressor is prevented. In this aspect, since the cooling temperature of the evaporator can be controlled by the second bypass, the working temperature range is considerably extended relative to the prior art.
The fourth object of the present invention is achieved by a modification of the above aspect. In the modification, an electromagnetic valve with a throttle valve is disposed within the cooling circuit for the condenser, whereby the temperature of the condenser is controlled. Thus, the controllable temperature range of the device is extended. Especially, at the starting mode, by stopping the cooling of the condenser, it becomes possible to rapidly raise the temperature of the device toward a predetermined value.
The fifth object of the present invention is achieved by a temperature control device for an automatic vending machine which stores articles therein and can change itself into a cooling mode and heating mode in relation to the season or other conditions. According to the characteristics of the device, it comprises at least one article storing compartment, and a refrigerating circuit having a compressor, condenser and an evaporator. A first electromagnetic valve is disposed at the inlet side of the evaporator, and a second electromagnetic valve is disposed at an intermediate point between the outlet side of the compressor and the inlet side of the condenser. A bypass circuit with a third electromagnetic valve is interposed between the outlet side of the compressor and the inlet side of the condenser so that this bypass circuit can bypass the second electromagnetic valve. A heat exchanger is disposed within the bypass circuit, and the evaporator and the heat exchanger are disposed within the article storing compartment. Thus, it is possible to select itself a heat absorbing mode by the evaporator or heat emitting mode by the heat exchanger through the exchange operation of the first, second and third electromagnetic valves.
Based upon the above characterics, according to the automatic vending machine of the invention, a conventional powerful electric heater for heating the articles is saved and a small heater may be substituted for the powerful heater. Thus, electric power and cost are considerably saved.
As a preferable modification of the above characteristics, a second bypass circuit is interposed between the downstream side of the condenser and the downstream side of the evaporator, and a capillary tube and a fourth electromagnetic valve are disposed within the second bypass circuit. Fluid flow in the second bypass circuit is controlled by the fourth electromagnetic valve so that the cooling temperature cooled by the evaporator is controlled. Thus the temperature control range is considerably extended.
Other characteristics and advantages of the present invention will be apparent from a reading of the following specification referring to the attached drawings.